Introduction of a fluid into a closed system can require devices and techniques that optimize the neatness and cleanliness of the introduction. The introduction of a fluid can be particularly challenging when the fluid has a color, odor, or is potentially dangerous. One type of fluid and system for which these issues can be important is in leak detection methods developed for fluid systems, such as climate control systems, such as heating, cooling, ventilating, and air conditioning systems, using dyes. Some methods employ emissive substances, such as, for example, fluorescent or phosphorescent dyes that are added to the refrigerants and/or lubricants of a climate control system. Suitable leak detection dyes include naphalimide, perylene, thioxanthane, coumarin, or fluorescein and derivatives thereof. Leaks can be detected by observing light emission from the dye at leak sites resulting from excitation of the dye with a light source having particular illumination characteristics (e.g. at wavelengths suitable to excite the dye and cause light emission from the dye). In general the dyes emit brightly when excited by light in the 190 to 700 nanometer wavelength range.